https://thehill.com/opinion/white-house/585301-how-old-is-too-old-to-be-president/ I thunk the Constitution has limitations on how old a person should be when they qualify to run for the President or VP (35). The life expectancy at the time wasn't as long as today. So I guess maybe the founders didn't think a person in their late 70s or 80s would run for the highest office. While performance is what counts, what are some thoughts on the subject?
Well, if we're considering this from an originalist perspective, then if the president were only doing what the founders had in mind, it would matter a lot less who had the job. (I realize that ship has long since sailed, but as recently as a century ago Calvin Coolidge would occasionally just sit on the White House porch in a rocking chair.)
From the perspective of a fellow that is 71 years old and in very good physical condition, I'd say that it would be better for the President of the USA to be younger than that. Although folks in their early 70's would likely be okay. If picking a maximum age to be starting a term, I'd probably lean toward about 70, maybe 68?
